Glossary of Terms:
 
delay
1) A time-offset or series of repeats applied to audio signals in order to create ambience or other effects.
2) An unwanted offset to an audio signal caused by processing.
3) An unwanted offset to a MIDI signal due to large amounts of simultaneous MIDI data.
4) An effects device used to simulate the delay of audio signals.
Source: Yamaha

Also refered as:
  echo
Related terms:
  chorus   echo   reverb